Your first image is an Internal Engine view.
Your second Image seems to be an OpenGL view.
Each of these views have different rules, stay with one type until you understand it well.
Have your tried to relocate the Sun to change the shadows? You might have the sun behind the building in that first image.
Look under Help for the Archicad 13 Reference Guide, Virtual Building, 3D Window. You will find this helpful.
Internal Engine will not reliably produce an intersection line at implied intersections.
An implied intersection is two objects overlapping each other in space, a real intersection is two objects terminating at the same line or point in space.
Real intersection = two walls with a clean "intersection".
Implied intersection = wall starting below a mesh and rising through it to become visible in 3D.
Then again there are some unknown programming quirks. When I need to have a line in 3D, ...ahem, when there "should" be a line in 3D, I have resorted to copying or moving the wall to new location, then returning it to old location to find it now has a line in 3D. Doesn't always work.